This invention relates generally to camshaft timing in internal combustion engines and relates more specifically to the means and methods used for altering the camshaft timing to improve performance and efficiency of the engine through a broad range of engine speeds.
It is known that by altering the camshaft timing or more specifically, altering the rotational phase relationship between the camshaft and the crankshaft in an internal combustion engine, the timing of the opening and closing of the intake and exhaust valves in relationship to the position of the pistons within the cylinders is altered. By altering this phase relationship and thereby advance or retard the camshaft timing conditions as the speed of the engine is adjusted, the engine performance and efficiency can be improved.
Examples of systems for altering the camshaft timing though a range of engine speeds are described in U.S. Pat. Nos. 4,955,330, 5,181,486 and 5,609,127. Each system of these referenced patents utilizes a rotating assembly which is interposed between the crankshaft and the camshaft for rotating about an axis at a rotational speed which corresponds with the speed of rotation of the engine camshaft. In addition, these rotating assemblies employ internal weights whose positions are adapted to change in response to centrifugal forces generated upon rotation of the assemblies. The amount of adjustment of the phase relationship between the camshaft and the crankshaft is dependent upon the position of the internal weights so that the faster the assembly is rotated, the greater the altering of the camshaft timing.
It is an object of the present invention to provide a new and improved assembly of the aforedescribed class for altering the camshaft timing of an internal combustion engine.
Another object of the present invention is to provide such an assembly for altering the phase relationship between the camshaft and the crankshaft of an internal combustion engine through a broad range of engine speeds.
Still another object of the present invention is to provide such an assembly whose construction and operation improves upon camshaft timing assemblies of the prior art.
Yet another object of the present invention is to provide such an assembly whose working components are compact and well-suited for use in a region adjacent an internal combustion engine where little space may be available.
A further object of the present invention is to provide such an assembly which is uncomplicated in construction and effective in operation.